Calendar display device for a timepiece

Abstract

Grand date calendar display device for a watch movement comprising a first disc and a second disc, arranged to display, on certain dates, first date values by combining symbols borne by said first disc and symbols borne by said second disc, and on other dates, second date values by symbols borne only by said second disc. The first disc is a modified units display disc, bearing a first series of symbols comprising a first sequence of at most nine first consecutive units numerals truncated by at least a second units numeral with respect to the complete series of ten units, and the second disc is a modified tens display disc including a second series of symbols for the display of at least the tens of the date, comprising at least one combination of two numerals formed of a tens numeral and a second units numeral.

Description

[0001]This application claims priority from European Patent Application No. 14200609.7 filed Dec. 30, 2014, the entire disclosure of which is hereby incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention concerns a calendar display mechanism, and in particular a “grand date” calendar display mechanism.BACKGROUND OF THE INVENTION[0003]Conventional calendar display devices for timepieces, and in particular wearable wristwatches, usually use an annular date-disc including 31 regularly distributed annular sectors, each of the sectors including an indication corresponding to one of possible dates of the month. The date-disc is indexed one position every day, so as to reveal through an aperture the date value corresponding to each day, which is formed of one or more numerals. The angular sector occupied by each indexing position is thus relatively limited (360 / 31 i.e. slightly less than 12 degrees), which greatly restricts the maximum size of the numbers that c...

AI Technical Summary

Benefits of technology

[0011]One advantage of the present invention is that it improves the balance of the indications borne by the two wheels, by moving some of the units indications to a modified tens disc. According to a preferred embodiment, the number of display indications borne by each of the wheels is exactly the same, which means that the size of the characters can be best adjusted for a combined display.

[0012]Another advantage of the proposed solution is that it employs a units disc, removing the need to use the complete sequence of numerals from 0 to 9 that has been used until now, by instead increasing the minimum sequence of indications borne by a modified tens disc, thereby facilitating and rendering more reliable each indexing of the latter.

[0013]According to a preferred embodiment, the two display discs are formed by rotating elements of substantially annular shape, i.e. whose display symbols cover a complete annular segment extending over 360 degrees during one cycle, typically of one month. When the indications of the two discs are arranged to cover the same annular surface and are superposed on each other for at least some dates, the display is confined in a small space and the control mechanism may even advantageously be incorporated at the centre of the ring for increased compactness.

Problems solved by technology

One drawback of this type of calendar mechanism is that it requires a very large number of parts, which are separate for the control and display mechanism, and therefore occupy too much space on the plate.

Further, the cross associated with the tens disc has a very small number of teeth, which is detrimental to gearing reliability due to the large angular steps required during each indexing operation.

The fact that the modified tens disc bears a larger number of symbols certainly facilitates the gearing mechanism, but because the sequence of indications relating to the units is arranged on a disc integral in rotation with a programme wheel having 31 sectors, the maximum size of the characters that can be displayed consequently still remains very limited.

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